Update render method to use reagent.dom.client's createRoot to be able to use React 18

[solita-nhuttu]

React 18 will behave like React 17 if references to React.DOM's render are found. To fully launch React 18, React.DOM/render references are to be replaced with reagent.dom.client's createRoot. Requires reagent upgrade to 1.2.0.

Refer to reagent 1.2.0: https://github.com/reagent-project/reagent/blob/master/CHANGELOG.md

Example usage I found online: https://stackoverflow.com/questions/72389560/how-to-rerender-reagent-ui-with-react-18-and-shadow-cljs-reload